Which of the following culture media functions as an enrichment medium? ________________?
Show answer Hide answer
Answer: B. Selenite F Broth
Explanation
Selenite F Broth is specifically formulated as an enrichment medium for cultivating Salmonella. It contains sodium selenite which inhibits the growth of normal commensal intestinal flora. This selective inhibition allows low numbers of pathogenic bacteria to multiply successfully. Enrichment media are liquid cultures designed to encourage the proliferation of specific target microorganisms. Stool samples often contain high numbers of normal flora that can mask enteric pathogens. Chemical additives suppress competing bacteria while providing necessary nutrients for the desired species.
Medical laboratories use selenite broth when processing stool specimens for suspected enteric infections. Isolating Salmonella promptly ensures accurate diagnosis and appropriate clinical patient management. Public health departments rely on these cultures to track outbreaks of foodborne illness. Blood agar acts as a general enriched differential medium rather than a selective enrichment broth. MacConkey agar functions primarily as a selective and differential medium for gram negative rods. Nutrient broth is a basic nonselective growth medium supporting many different bacterial species.
Related questions
Q1. Which bacterial enzyme is necessary for pathogenic staphylococci to induce plasma clot formation? _____________?
Show answer Hide answer
Answer: C. Coagulase
Coagulase is an enzymatic virulence factor produced by pathogenic staphylococci to induce plasma clot formation. The enzyme converts soluble fibrinogen into insoluble fibrin threads that coat the bacterial cells. Clot fo...
Q2. Which of the following vaccines is NOT classified as a live attenuated vaccine ?
Show answer Hide answer
Answer: D. Cholera
Cholera vaccines are typically formulated using killed whole bacteria or purified subunits. Inactivated vaccine preparations lack live replicating organisms capable of causing infection. This manufacturing approach ensur...
Q3. Which of the listed immunizations is a live vaccine? _____________?
Show answer Hide answer
Answer: D. HDCV
Human Diploid Cell Vaccine (HDCV) is an inactivated rabies vaccine, making it a killed rather than a live vaccine among the choices.
Q4. Which of the following statements regarding amoebic liver disease is accurate ?
Show answer Hide answer
Answer: C. Trophozoites can be visualized in the pus
Amoebic liver abscesses produce characteristic necrotic liquefaction commonly described as anchovy paste pus. Entamoeba histolytica trophozoites can frequently be visualized microscopically within this aspirated abscess...
Q5. How is a complete virion defined? ______________?
Show answer Hide answer
Answer: A. Extracellular infectious virus particle
A complete extracellular infectious viral particle is structurally referred to as a virion. Virions consist of a nucleic acid genome enclosed within a protective protein capsid shell. This infectious extracellular form e...
Q6. Which of the following facts regarding the pasteurization process is true ?
Show answer Hide answer
Answer: B. It kills all bacteria except thermoduric bacteria
Pasteurization utilizes controlled heat to eliminate vegetative pathogens while sparing heat-resistant spores. Thermoduric microorganisms possess robust cellular structures enabling survival through standard heating cycl...